Resistor support



March 28, 1950 M. s cso 2,502,044

RESISTOR SUPPORT Filed Nov. 19, 1946 6 Sheets-Sheet l N 4 2 5 i 1:. i l .;.:'f '3 l FIG I m. xwm

I NVENTOR March 28, 1950 H. M. ISAACSON RESISTOR SUPPORT 6 Sheets-Sheet 2 Filed Nov. 19, 1946 FIG 3A FIG 2 FIG 3B INVENTOR March 28, 1950 H. M. ISAACSON 2,502,044

RESISTOR SUPPORT Filed Nov. 19, 1946 e Sheets-Sheet 5 Mn. xwmm INVENTOR March 28, 1950 H. M. ISAACSON 2 ,502,044

RESISTOR SUPPORT Filed Nov. 19, 1946 6 Sheets-Sheet 4 l4 f L l7 l5- l6 l7 14 (5 C5 FIG 8 AM INVENTOR March 28, 1950 H. M. lsAAcsoN 2,502,044

RESISTOR SUPPORT Filed Nov. 19, 1946 6 Sheets-Sheet 5 l i L n J W L I 1- Fr I9 19 F IG 9 INVENTOR March 28, 1950 H. M. ISAACSON 2,502,044

RESISTOR SUPPORT Filed Nov 19, 1946 6 Sheets-Sheet 6 FIG l0 FIG 7 m QWWW INV EN TOR H l l l l l H l I Patented Mar. 28, 1950 UNITED STATES PATENT OFFICE RESISTOR SUPPORT Herbert M. Isaacson, Buffalo, N. Y.

Application November 19, 1946, Serial No. 710,767

2 Claims. 1

This invention relates to an improved form of electrical resistance air heaters, and more particularly to an improvement in the structure of the resistance element and its supporting structure.

One object of the invention is to provide a structure of minimum mass in order to minimize heating time lag due to thermal inertia.

Another object of the invention is to provide a structure that will introduce minimum impediment to the flow of air over the heating element.

Another object of the invention is to provide a structure that will be simple and low in cost to manufacture, and that will be sturdy and long-lived in service.

Another object of the invention is to provide a structure that will avoid the use of ceramics, now commonly employed, because of the difficulties in attaining the previously mentioned obj eetives imposed by their use.

Another object of the invention is to provide a structure that will use mica plate or an equivalent material as the insulating support for the resistance element without suiiering the usual difiiculties attendant upon the use of such material by reason of its mechanical and structural limitations.

Another object of the invention is to provide a heating element structure that efiectively exchanges its heat with the surrounding air without 3 major dependence upon radiation for dissipation of its heat energy.

Another object of the invention is to provide a heating element structure that lends itself for incorporation in either a convection type air heater or a driven fan type air heater.

The following describes preferred forms of the invention, but it is to be understood that other forms are possible without departing from the spirit of the invention.

Figure 1 shows an isometric view of the resistance element supporting structure, with resistance element wound in place, mounted within a duct. Figure 2 is a plan view of the mica insulating member I of Figure 1. Figure 3A shows the mica clamping member 2 of Figure 1 before it is formed. Figure 3B shows side and end views of mica clamping member 2 after being formed and with mica insulating member I clamped in it. Figure 4 shows an exploded view of the terminal 6 of Figure 1. Figures 5 and 6 show respectively end and side views of another form of the invention in which the mica members are supported in a structure formed from a single piece of metal. Figure 7 shows the blanked shape of such a metal structure before forming. Figures 8 and 9 show another form of such a suporting structure blanked and formed. from one piece of metal. Figure 10 shows such an electrical resistance element mounted in a duct, the whole being mounted within an enclosing case with driven fan to form a space heater. Figure 11 shows another arrangement of resistance element and duct within an enclosing case to form a space heater of the air convection type.

Referring to Figures 1 and 2, mica strips 1 are clamped in metal members 2, with the notches in the mica strips I starting and extending beyond the edges of the channel formed by metal members 2. Sub-assemblies of mica strips i clamped in metal supports 2, as shown in Figure 3B, are fastened, preferably by spot welding, to support members 3 and 4. Terminal support 5 with terminals 6 mounted on it are also fastened to support members 3 or 4. A resistance element l is wound on this structure as shown in Figure 1, with its ends fastened to terminals 6.

While resistance element 7 is shown as a fiat ribbon, it may have any shaped cross section. Also, instead of being straight between support points it may be in the form of a spaced helix, or crimped, or given any other configuration desired. Further, although four mica insulating members I are shown for supporting the resistance element 7, three or more may be used, with substantially equal angular spacing between them.

The notches in mica strips I are of such size, shape, and spacing as required to support and restrain the resistance winding 1. It is desirable to have the sides of the notches sloping slightly outwardly to facilitate the winding of the resistance element 1, particularly if it be of fiat ribbon instead of round wire. The depth of the notches is made suflicient to restrain the winding within the notches even when the element expands and lengthens upon heating.

Figure 4 shows an exploded view of the details of the terminal support and assembly, 5 and 6 of Figure 1. Mica washers 8 and 9, and lug I!) are fastened together in support member 5 by eyelet ll, mica washer 9 fitting in hole 13 of support member 5. Lug I0 is thereby electrically insulated from member 5. These terminals serve as anchoring means for the ends of the resistance element winding 1 and for the external leads carrying electric current to the winding. Connection of the ends of the resistance element winding and of the external connecting leads is desirably made by silver soldering.

Figure shows an end view of the one piece element support structure formed from the blank shape shown in Figure 7, with mica strips 1 clamped in place. U-shaped mica clamping members l4 serve the same function as members 2 of the structure shown in Figure 1. Similarly, integral arms 15 serve the same function as mem bars 3 and 4 of Figure 1.

Figure 6 shows a side view of the same one piece structure. An integral terminal support It with holes I"! serves the same function as terminal support 5 and holes l3 of Figures 1 and 4. Obvious details, such as provision for mounting feet in the same one piece stamping, have been omitted for the sake of simplicity and clarity.

Figure 8 shows a side view of another one piece element support structure, formed from the blank shape shown in Figure 9. U-shaped members l8 clamp mica pieces l. Integral members I!) serve the same function as members 3 and 4 of Figure 1. Terminal support member 20 with holes 2! serve the same function as support 5 and holes 13 of Figures 1 and l.

Resistance elements wound on such support structures formed from one piece of metal, and then mountedin a duct such as duct 12 of Figure 1, make an equivalent overall assembly to that shown by Figure 1. It will be seen that in all the structures described, the stresses imposed by the resistance element winding 1 are essentially compressive ones imposed upon the width dimension of the mica strips, and that objectionable distortion of the mica strips is prevented by the reinforcement and rigidity imparted by the metal sup-port members into which the mica strips are clamped. Neither is dependance made upon the binder of the mica plate, which often burns out in use. This combination of mica strips clamped in metal support members in the manner described secures the electrical and heat insulative qualities of mica without incurring its poor and undesirable mechanical characteristics. Also, in all of the structures described the thin edges rather than the widths of the various component elements are presented to an axial flow of air through the structure, thereby minimizing the impediment to such an air flow. At the same time the full area of the resistance winding is exposed to the flowing air for transi er of its heat.

When an assembly such as that of Figure 1 is mounted in an enclosing case as in Figure 10 or Figure 11 it forms an excellent space or air heater. In such a heater, heated air passes within the confines of the duct 12 and then outwardly through the grilled openings of the enclosing case, thereby keeping the enclosing case at a lower temperature than if the heated air were free to swirl around within it. In Figure 10 cool air is sucked into the enclosing case by motor driven fan blade 22, passed over the heated resistance element within duct l2 where it becomes heated, and is then forced out of the enclosing case through suitable grilled opening 23. In Figure 11 the air circulation is obtained by convection rather than by a motor driven fan. The confining and chimney effect of duct l2 increases the velocity of the heated air movement and also prevents the enclosing case from becoming objectionably hot. Louvered openings 24 provide for ingress of cool air and egress of heated air Obvious details such as wiring, mounting means, etc. have been purposely omitted from the drawings for the sak of simplicity and clarity.

Having thus set forth the means whereby the objects of my invention are attained, I claim as new and patentable:

1. An electrical resistance winding support, said support including as a component element a mica strip, said mica strip being clamped for substantially its full length between the sides of metal channel, said mica strip having notches along a lengthwise edge to anchor and support a resistance heating wire, and said notches being wholly outside of said metal channel.

2. In an electrical resistance winding support, the combination of notched mica strips, and metal channels, said mica strips being clamped for substantially their whole length between the sides of said metal channels and with their notches lying wholly outside of said metal channels, and a metal frame, said frame positioning said channels so that an electrical resistance wire can be wound from notch to notch of adjacent mica strips to form a helical winding.

HERBERT M. ISAACSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,520,241 Happe Dec. 23, 1924 1,620,767 Johnson Mar. 15, 1927 1,998,670 Goshorn et a1 Apr. 23, 1935 

